Yes you are correct. When I the truck works correctly, it shifts freely from park to drive. The problem I am encountering now again, is that the truck will shift freely from park to reverse and neutral. But will not shift by engaging the column lever to drive.. When in neutral it rolls. When in reverse it moves. But cannot engage into drive using the column lever. No to the parking break question as this is a plow truck.

APPLY PARK BRAKE CHOCK WHEELS, shift to net.,get under truck at drivers door look at linkage on the side of trans. to see if any obstruction,ice ect. at shift link.If none pop off shift cable and move link by hand, or plires to see if it moves then. Now with that unhooked try the shift lever to determine where problem is! One or the other should not work propperly. Possible net. safety switch, most likely suspect, at the linkage on trans or shift mechanism inside column. To rule out cable it will have to be unhooked inside of column, least likely suspect.If linkage doesn't move at trans with cable off can 'carefully' (easily damaged) remove netural switch to see if the problem is deeper.'Or get it in gear and go SEE A MECHANIC!! IF REMOVED, REPLACE ALL PARTS BEFORE!Was it cold weather the other time this happened? And had you been plowing snow then?

Yes it was cold before when this first happened. The Truck was used and then sat a few days. I was still using it and then id locked up. I revcersed out of the way to park it to have it looked at, and when the mechanic came he siad it worked fine. We initially though that maybe some slush or snow packed in while the truck was hot, then froze causing the problem but then melted again.

This second time I had used it without incident several times... Parked it after last storm and it was locked up the next time it was needed. I have warmed the truck for 1/2 hour and was still not able to shift it into drive. I tried purring it into @ Wheel Drive, 4WHigh and 4 WLow - It will shift P - N and R fine all day long.

I once saw a plow truch that had cut open the floor boards and fashioned some threaded bar up through the center for shifting an automatic - is this a fairly common problem with checvy truck transmissions?